Zeolites are crystalline alumino silicates which embrace pores of the order of molecular sizes, and membranes made up of zeolites are widely used as molecular sieves because of their property of selectively allowing molecules to pass through themselves depending on the molecular size or shape. It is known that good energy efficiency can be attained when the zeolite membrane is used for separation between water and organic solvent in a mixed liquid thereof.
Since zeolite membrane does not have sufficient mechanical strength in itself, the zeolite membrane is generally formed on a surface of a porous ceramic tube. When assembling such a zeolite membrane-covered ceramic tube into a module, it is often that a metal tube is jointed to an end of the ceramic tube. Assembling the ceramic tube into the module becomes easy by virtue of such a construction.
The conventional way of jointing the zeolite membrane-covered ceramic tube and the metal tube will be explained.
First, a zeolite membrane-covered ceramic tube, and a metal tube having an outer diameter which is about the same with that of the ceramic tube are provided. A thermally shrinkable tube of which inner diameter is slightly larger than the outer diameter of the metal tube is also provided.
Next, to one end of the thermally shrinkable tube, an end of the zeolite membrane-covered ceramic tube is inserted, and to another end of the thermally shrinkable tube, an end of the metal tube is inserted. Then, by heating the thermally shrinkable tube, the thermally shrinkable tube is allowed to shrink in the direction of decreasing the inner diameter thereof in order to joint the zeolite membrane-covered ceramic tube and the metal tube (See, Patent literature 1).    Patent literature 1: JP 8-131782 A (The 8th paragraph)